Planet Michael publisher SEE Virtual Worlds has purchased the rights to Planet Calypso, the first planet from MindArk's free-to-play, client-based MMORPG Entropia Universe, for $6 million.

Launched with Entropia Universe in 2003, Planet Calypso has attracted over 950,000 registered accounts from more than 200 countries and territories to its futuristic setting, in which players work to establish a new virtual civilization with a human colony on an alien world.

Entropia Universe and Planet Calypso feature a "Real Cash Economy" with virtual currency that players can withdraw as real-world funds (10:1 exchange rate with the U.S. dollar). In 2010 alone, that economy supported $428 million in player-to-player transactions.

SEE Virtual Worlds has previously announced plans to launch Planet Michael, a massively multiplayer online game inspired by late pop star Michael Jackson, as well as an MMO based on Universal Pictures's classic movie monsters (e.g. Frankenstein, Wolf Man).

Both of those free-to-play worlds will be built on MindArk's Entropia platform and also feature real money trading. SEE Virtual Worlds has previously expressed an interest in creating a "virtual reality universe of connected planets", each planet tied to media licenses.

The company also announced that it's acquired the assets of MindArk subsidiary First Planet Company, which will now be branded as SEE Digital Studios. The Gothenburg-based developer will continue to maintain Planet Calypso while taking in new staff to work on Planet Michael.

"As we move into 2011 and beyond, SEE Virtual Worlds will continue to bring its innovative product offerings to the virtual world marketplace," says SEE Virtual Worlds CEO Martin Biallas.

He adds, "We know that virtual worlds are extremely lucrative and much of our success will be strengthened by working with Mindark and the added experience that First Planet Company brings to the process, having developed the most successful planet in the Entropia Universe to date."